In a study published in the Proceedings of the National Academy of Sciences (https://doi.org/10.1073/pnas.2315167121), Dr. Harry Chao from the Shih Lab and researchers in Stanford University have provided new insights into the brain’s default mode network (DMN), particularly focusing on the retrosplenial cortex’s role in spatial exploration. Traditionally, the DMN has been studied under behaviorally restricted conditions. This study breaks new ground by examining the network’s function in freely moving rats, offering a more dynamic view of its operation in naturalistic behaviors.
Using advanced multisite fiber photometry recording of neuronal activity, video tracking, and computational modeling, the team discovered that the DMN, contrary to being suppressed during active tasks, plays a significant role in spatial navigation. This finding challenges the prevailing notion that the DMN is only active when the brain is at rest. The research revealed a hierarchy within the DMN, with the retrosplenial cortex being a key node. This cortical area, along with others in the DMN, was found to be synchronized during spatial exploration, indicating its active participation in processing real-world spatial exploration.
The study’s innovative approach of observing the DMN in action during unscripted, exploratory behavior of animals has provided valuable insights into how this brain network processes spatial and environmental information. The results underscore the importance of studying brain networks in conditions that closely resemble their natural functioning state, paving the way for a deeper understanding of the DMN’s role in both health and disease.